I'm trying to better understand the Schwartzian Tranform (sorting a list by computable field). I've read the explanation in the Perl Cookbook, 2d ed. recipe 4.16. I also enjoyed Randal's 1996 article in the Unix Review, which describes a sortable-hash technique before it goes on to show the map-sort-map transform technique. The sortable-hash technique intrigues me.
Other than coolness and nicer-looking code, what is the advantage of this: